Tungsten Insertion Layer for pSOT Thermal Stability

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Solution Overview

Problem

Perpendicular spin orbit torque (pSOT) devices face challenges in achieving thermal stability and retention of perpendicular magnetic anisotropy after back end processing, particularly due to diffusion issues at high temperatures.

Innovation Solution

Incorporating a predominantly tungsten layer between the SOT electrode and the free magnetic material layer in pSOT devices, which acts as a diffusion barrier and enhances the thermal stability and retention of magnetic material layers by preventing boron diffusion, while also simplifying fabrication and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional SOT electrode structure is used without additional barrier layers, then the device structure remains simple, but thermal stability and retention of perpendicular magnetic anisotropy deteriorate during back end processing at high temperatures

Engineering Contradiction:

Improvethermal stabilityVSAvoiddevice structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A predominantly tungsten layer is inserted between the SOT electrode and the free magnetic material layer to act as a diffusion barrier. This intermediary layer prevents boron diffusion from the magnetic material to the SOT electrode during high-temperature back end processing, thereby maintaining thermal stability and perpendicular magnetic anisotropy retention without significantly complicating the overall device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the SOT electrode is directly coupled with the free magnetic material layer, then fabrication is simpler, but boron diffusion occurs at high temperatures causing loss of magnetic properties

Engineering Contradiction:

Improveretention of magnetic propertiesVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The predominantly tungsten layer serves as a diffusion barrier positioned between the SOT electrode and free magnetic material layer. This barrier prevents boron atoms from diffusing into the SOT electrode during high-temperature processing, thereby preserving the magnetic properties of the free magnetic material layer while adding only a single intermediate layer to the structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If no diffusion barrier is used, then manufacturing process is simpler and costs are lower, but thermal stability during back end processing deteriorates

Engineering Contradiction:

Improvethermal stabilityVSAvoidfabrication process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

A predominantly tungsten layer is introduced as a diffusion barrier between the SOT electrode and free magnetic material layer. This single additional layer effectively blocks boron diffusion during high-temperature back end processing, improving thermal stability while adding minimal complexity to the fabrication process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The device employs a composite structure where a predominantly tungsten layer is combined with the SOT electrode and free magnetic material layer. This composite approach leverages the diffusion barrier properties of tungsten to protect the magnetic material from boron loss during high-temperature processing, thereby enhancing overall device reliability.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The predominantly tungsten layer improves the thermal stability and retention of magnetic material layers, maintaining the composition and magnetic properties of pSOT devices during high-temperature processing, thereby enhancing the overall performance and reliability of pSOT memory devices.

Implementation Method 1

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

Perpendicular spin orbit torque (pSOT) devices include an SOT electrode coupled with a magnetic junction such as a magnetic tunnel junction (MTJ)

Methodology Applied

Scientific EffectSpin orbit torque:

Implementation Method 3

When the magnetization directions of the free and fixed magnets are parallel the MTJ resistance is in a low state and when the magnetization directions are antiparallel the MTJ resistance is in a high state

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS11508903B2Spin orbit torque device with insertion layer between spin orbit torque electrode and free layer for improved performance

Publication Date: 2022.11.22 INTEL CORP

AI summary

An insertion layer for perpendicular spin orbit torque (SOT) memory devices between the SOT electrode and the free magnetic layer, memory devices and computing platforms employing such insertion layers, and methods for forming them are discussed. The insertion layer is predominantly tungsten and improves thermal stability and perpendicular magnetic anisotropy in the free magnetic layer.